It is difficult. I find it difficult too. Have you tried praying, asking God to give you opportunities to talk to them? You don't need to give them a big long speech, but just a few words here and there. Sharing your testimonies. My sister sharing a testimony with me, is what got me to turn to Jesus. Testimonies are powerful things. Leading by example aswell. If they see the way you don't react in a situation, where they may have completely mouthed off etc, that can help too. It's impressive to see someone not completely lose it where they might have.